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CM's questions, answered (Miscellaneous)

posted by cm(R) Homepage E-mail, Düsseldorf, Germany, 12.12.2009, 22:40

> - Case DOS 8 (checked the version of IO.SYS for floppies, since the
> regular one does not even process a Config.Sys hence is of no relevance) :
> easiest, DOSCode = FFFFh. Seems to be hardwired, HiMem is built-into IO.SYS
> and DOS is always loaded in the HMA (DOS=LOW has no effect).

I'd still rather use the other method here. If it works just as well, handling MS-DOS 8 separately only adds unnecessary code. Also, the XMM might find the HMA to be unavailable somehow and the kernel would then probably revert to another location. (Might be due to unknown A20 switch method, or only 1 MiB of physical memory. What are the odds of either with 386+ PCs?)

> Amusingly Microsoft seems to ignore this fact and includes a copy of
> HIMEM.SYS on their boot disquettes, which is just wasting space (unless
> you want to give HIMEM extra parameters, you may delete it).

Don't they load the internal driver unconditionally (before processing CONFIG.SYS), thus rendering the executable completely useless?

> - Case DOS 7.x : peek into DOSData, there is

Where? Or rather: How do you find that table? If I'd want to find it now, I'd look at the interrupt vector for one of the unaltered interrupts in my debugger. Your way might be able to find the table even with all these interrupts hooked.

> I think I will provide the source code per request rather than make it
> downloadable anonymously.

I'll just state it flat out: I do not agree with this; I don't see a reason to exclude the source generally but to make it available per request nonetheless. (Of course this still is better than not providing source at all, therefore I thank you. I just don't see why not to provide it directly.)



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